Extractor and bolt for a firearm

ABSTRACT

A bolt, having: an extractor pivotally thereto for movement between at least a first position and a second position, a hook member located at a distal end of the extractor, wherein the hook member is at least partially received within a pocket on a muzzle end of the bolt and the hook member moves away from a center line of the bolt as the hook member is moved from the first position towards the second position, wherein a bottom of the pocket is recessed within a first range A in a first direction from the muzzle and the hook member has an axial thickness parallel to the center line within a first range A′ and wherein the hook member is flush with the muzzle when the hook member is in the second position.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Provisional Patent Application No. 61/475,487 filed Apr. 14, 2011, the contents of which are incorporated herein by reference thereto.

BACKGROUND

Various embodiments of the present invention are related to a bolt and extractor for a firearm and, more particularly, to an improved bolt and extractor configuration.

Automatic and/or semiautomatic firearms comprise complex mechanisms that are subject to continuous cycling each time a round is fired as such, certain components are subject to wear and must be cleaned and/or replaced on a periodic basis. Accordingly, it is desirable to provide a firearm or components of a firearm that withstand excessive cycling and thus extend the useful life of such components in order to reduce the need for replacement.

SUMMARY

In one exemplary embodiment, a bolt for a firearm is provided herein, the bolt having: an extractor pivotally mounted to the bolt for movement between at least a first position and a second position, the extractor having a hook member located at a distal end of the extractor, wherein the hook member is at least partially received within a pocket on a muzzle end of the bolt and the hook member moves away from a center line of bolt as the hook member is moved from the first position towards the second position, wherein a bottom of the pocket is recessed at least a first dimension within a first range A that is greater than 0.130 inches and less than 0.200 inches in a first direction from the muzzle end of the bolt and the hook member has an axial thickness parallel to the center line of the bolt within a first range A′ that is greater than 0.050 inches and less than 0.130 inches and wherein the hook member is flush with the muzzle end of the bolt when the hook member is in the second position.

In another embodiment, a bolt for a firearm is provided the bolt having an extractor pivotally mounted to the bolt for movement between at least a first position and a second position, the extractor having a hook member located at a distal end of the extractor, wherein the hook member is at least partially received within a pocket on a muzzle end of the bolt and the hook member moves away from a center line of bolt as the hook member is moved from the first position towards the second position, wherein a bottom of the pocket is recessed 0.145 inches from the muzzle end in a first direction parallel to the center line of the bolt and the hook member has an axial thickness of 0.075 inches in the first direction and wherein the hook member is flush with the muzzle end of the bolt.

Additional features and advantages are realized through the techniques of the present invention. Other embodiments and aspects of the invention are described in detail herein and are considered a part of the claimed invention. For a better understanding of the invention with advantages and features, refer to the description and to the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention, in accordance with preferred and various embodiments, together with further objects and advantages thereof, is more particularly described in the following detailed description taken in conjunction with the accompanying drawings in which:

FIG. 1 is a cross-sectional view of a bolt and extractor in accordance with an exemplary embodiment of the present invention;

FIGS. 1A-1C are additional partial view of the bolt and extractor in accordance with an exemplary embodiment of the present invention; and

FIG. 2 is a view of a firearm according to a non-limiting exemplary embodiment of the present invention.

The detailed description explains various embodiments of the present invention, together with advantages and features, by way of example with reference to the drawings.

DETAILED DESCRIPTION

Referring now to FIGS. 1 and 1A-1C, a bolt 10 for a firearm 11 is illustrated. One non-limiting example of a firearm utilizing bolt 10 is illustrated in United States Patent Publication Number 2010/0300277 in the name of Hochstrate et al., the contents of which are incorporated herein by reference thereto.

As is known in the related arts, bolt 10 is received within a bolt carrier that is slidably received within an upper receiver of a firearm wherein the bolt carrier is acted upon by expanding gases generated by the firing of a bullet from a cartridge.

In general, the extractor pivots on the bolt to engage a cartridge with a hook and after firing of that cartridge the engagement of the hook with the cartridge is used to empty or extract the empty case from the barrel such that a new unfired cartridge can be inserted into the barrel by the bolt.

In order for the bolt to engage the cartridge a portion of the cartridge is received within a pocket on the muzzle end of the bolt and the hook engages a rim of the cartridge when it is received within the pocket. The extractor hook pivots away from the center axis of the bolt to allow for insertion of the cartridge into the bolt and then pivots back towards the center axis by a spring biasing force in order to engage the cartridge rim once the cartridge is fully seated in the pocket of the bolt. At this point the extractor hook is forced into a groove of the cartridge. After the cartridge is fired the action of the firearm moves the bolt rearward and the hook which is now fully engaged with the case rim pulls the case out of the chamber. However, the shear forces generated by the resistance of the case removal from the chamber and the rearward movement of the bolt pull on the extractor may cause the extractor to fail prematurely. Accordingly, it is desirable to provide an extractor hook and bolt design that can withstand numerous cycling events in order to avoid premature extractor hook replacement due to hook failure.

As illustrated in FIG. 1, bolt 10 has an extractor 12 that is pivotally or movably mounted to the bolt for movement between a first position and at least a second position wherein the second position corresponds to the extractor engaging a cartridge received within a portion of the bolt and the first position corresponds to the location of the extractor when the bolt is not engaging a cartridge. It being understood that the extractor will have to move to at least one other position in order to allow a cartridge to be received within the bolt. Thus, movement of the hook member 14 in the direction of arrows 17 is contemplated.

As illustrated and in order for the extractor to engage the cartridge, the extractor has a hook member 14 located at a distal end 16 of the extractor 12. The hook member 14 is at least partially received within a seat or pocket 18 recessed on a forward or muzzle end 20 of the bolt. The hook member is flush with the muzzle end of the bolt when it is in the second position and the hook member moves away from a center line 21 of the bolt as the hook is moved from the first position to allow for a portion of a cartridge 24 to be received within the pocket. Thereafter, the hook member moves back towards the center line 21 and engages a rim 22 of the cartridge 24.

After the cartridge is fired the action of the firearm moves the bolt rearward with respect to a forward end or muzzle of the firearm and the hook member which is now fully engaged with the case or cartridge rim 22 pulls the case or cartridge out of the chamber.

In accordance with an exemplary embodiment and in order to provide a more robust hook member 14 of the extractor 12 a bottom 30 of the seat or pocket 18 is recessed at least a first dimension 32 from the forward or muzzle end 20 of the bolt in a first direction illustrated by arrow 33, which is parallel to the central axis or center line 21 of bolt. In addition, the hook member has an axial thickness 34 that is also parallel to the central axis or center line 21 of bolt. As will be detailed below, the axial thickness of the hook member is a function of the depth of the bottom of the pocket from the muzzle end of the bolt in the direction of arrow 33.

In accordance with one embodiment, the first dimension is within a first range A that is greater than 0.130 inches and less than 0.200 inches in the first direction from the forward or muzzle end of the bolt. Still further and in another embodiment the first dimension is within a second range B that is greater than 0.135 inches and less than 0.175 inches in the first direction from the forward or muzzle end of the bolt. In yet another embodiment, the first dimension is within a third range C that is greater than 0.140 inches and less than 0.150 inches in the first direction from the forward or muzzle end of the bolt. One exemplary dimension of the first dimension is 0.145 inches. Of course, it is understood that numerous nested ranges and dimensions within the aforementioned ranges are contemplated to be within the scope of exemplary embodiments of the present invention.

In addition and in conjunction with the dimension of the depth of the seat or pocket 18 of the bolt the dimension or axial thickness of the hook member hook member is within a first range A′ that is greater than 0.050 inches and less than 0.130 inches when the first dimension of the seat is within range A. In another embodiment and in conjunction with the dimension of the depth of the seat or pocket 18 of the bolt, the dimension or axial thickness of the hook member is within a second range B′ that is greater than 0.055 inches and less than 0.105 inches when the first dimension of the seat or pocket is within range B. Still further and in another embodiment, the dimension or axial thickness of the hook member hook member is within a third range C′ that is greater than 0.060 inches and less than 0.080 inches when the first dimension of the seat or pocket is within range C.

One exemplary dimension or axial thickness of the hook member is 0.075 inches when the first dimension or depth of the pocket is 0.145 inches. Of course, it is understood that numerous nested ranges and dimensions within the aforementioned ranges are contemplated to be within the scope of exemplary embodiments of the present invention. The aforementioned ranges and dimensions have shown an improved working life expectancy of the extractor hook without the deleterious effects from extending the cartridge to far from the end of the barrel.

In addition and as illustrated in FIG. 1, the hook member is flush with the muzzle portion of the bolt when the hook member is in the second position such that no portion of the hook member extends past the forward or muzzle end of the bolt.

In order for the extractor 12 to engage the rim 22 of the cartridge the hook member of the extractor is spring biased towards the center line of the bolt by a spring 36 that is located on the bolt. In one implementation, the hook member is located at a first end of the extractor and the spring is located to provide a biasing force to an opposite end of the extractor.

In one embodiment, the bolt 10 and extractor 12 are configured for use with a .308 caliber round or 7.62 mm NATO round as currently configured. However, the bolt and extractor may be configured for use with numerous other sized rounds for example, one non-limiting other sized round may be a 5.56 mm NATO round.

While the invention has been described with reference to an exemplary embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the present application. 

1. A bolt for a firearm, comprising: an extractor pivotally mounted to the bolt for movement between at least a first position and a second position, the extractor having a hook member located at a distal end of the extractor, wherein the hook member is at least partially received within a pocket on a muzzle end of the bolt and the hook member moves away from a center line of the bolt as the hook member is moved from the first position towards the second position, wherein a bottom of the pocket is recessed at least a first dimension within a first range A that is greater than 0.130 inches and less than 0.200 inches in a first direction from the muzzle end of the bolt and the hook member has an axial thickness parallel to the center line of the bolt within a first range A′ that is greater than 0.050 inches and less than 0.130 inches and wherein the hook member is flush with the muzzle end of the bolt when the hook member is in the second position.
 2. The bolt as in claim 1, wherein the hook member of the extractor is spring biased towards the center line of the bolt by a spring located on the bolt.
 3. The bolt as in claim 1, wherein the hook member is located at a first end of the extractor and the spring is located to provide a biasing force to an opposite end of the extractor.
 4. The bolt as in claim 3, wherein the extractor is pivotally mounted to the bolt a location between the first end and the opposite end of the extractor.
 5. The bolt as in claim 1, wherein the bolt is configured for use in a semiautomatic or automatic firearm.
 6. The bolt as in claim 1, wherein the bolt is configured for use in a semiautomatic or automatic firearm rifle.
 7. The bolt as in claim 5, wherein the hook member of the extractor is spring biased toward the center line by a spring located on the bolt.
 8. The bolt as in claim 7, wherein the hook member is located at a first end of the extractor and the spring is located to provide a biasing force to an opposite end of the extractor.
 9. The bolt as in claim 8, wherein the extractor is pivotally mounted to the bolt a location between the first end and the opposite end of the extractor.
 10. The bolt as in claim 1, wherein the bolt is configured for use with a .308 caliber round.
 11. The bolt as in claim 1, wherein the first range A is greater than 0.135 inches and less than 0.175 inches and the first range A′ is greater than 0.055 inches and less than 0.105 inches.
 12. The bolt as in claim 1, wherein the first range A is greater than 0.140 inches and less than 0.150 inches and the first range A′ is greater than 0.060 inches and less than 0.080 inches.
 13. The bolt as in claim 11, wherein the hook member of the extractor is spring biased towards the center line of the bolt by a spring located on the bolt and wherein the hook member is located at a first end of the extractor and the spring is located to provide a biasing force to an opposite end of the extractor.
 14. The bolt as in claim 13, wherein the extractor is pivotally mounted to the bolt a location between the first end and the opposite end of the extractor.
 15. The bolt as in claim 11, wherein the bolt is configured for use in a semiautomatic or automatic firearm.
 16. The bolt as in claim 12, wherein the hook member of the extractor is spring biased towards the center line by a spring located on the bolt and wherein the hook member is located at a first end of the extractor and the spring is located to provide a biasing force to an opposite end of the extractor.
 17. The bolt as in claim 16, wherein the bolt is configured for use in a semiautomatic or automatic firearm.
 18. The bolt as in claim 17, wherein the bolt is configured for use with a .308 caliber round.
 19. A bolt for a firearm, comprising: an extractor pivotally mounted to the bolt for movement between a first position and a second position, the extractor having a hook member located at a distal end of the extractor, wherein the hook member is at least partially received within a pocket on a muzzle end of the bolt and the hook member moves away from a center line of the bolt as the hook member is moved from the first position towards the second position, wherein a bottom of the pocket is recessed at least a first dimension of 0.145 inches in a first direction from the muzzle end of the bolt and the hook member has an axial thickness of 0.075 inches in the first direction and parallel to the center line of the bolt and wherein the hook member is flush with the muzzle end of the bolt when it is in the second position.
 20. The bolt as in claim 19, wherein the hook member of the extractor is spring biased towards the center line of the bolt by a spring located on the bolt and wherein the hook member is located at a first end of the extractor and the spring is located to provide a biasing force to an opposite end of the extractor and wherein the extractor is pivotally mounted to the bolt a location between the first end and the opposite end of the extractor and wherein the bolt is configured for use in a semiautomatic or automatic firearm and wherein the bolt is configured for use with a .308 caliber round. 